title: Parity, time since last live birth and long-term functional outcome: a study of women participating in the Norfolk Arthritis Register.
abstract: OBJECTIVE
  To investigate the relationship between pre-symptom onset live births and functional outcome in women with inflammatory polyarthritis (IP).
  
  
  METHODS
  1872 women with no subsequent pregnancies were registered with the Norfolk Arthritis Register between 1990 and 2004 and followed-up for a median of 5 years. Functional disability over time was assessed by Health Assessment Questionnaire (HAQ). The number and calendar year of past live births were recorded. Differences in HAQ score over time by parity and time since last live birth (latency), adjusted for age and symptom duration, were examined using linear random effects models. The results were then adjusted for a number of potential confounders.
  
  
  RESULTS
  1553 women (83%) had ≥1 live births before symptom onset. The median latency was 26 years (IQR 16-35). Parous women had significantly lower HAQ scores over time than nulliparous women (-0.19, 95% CI -0.32 to -0.06). Increasing latency was associated with increasing HAQ score; the mean HAQ score of women with a latency of approximately 32 years was the same as for nulliparous women. This was independent of autoantibody status, socioeconomic status, smoking history and comorbidity.
  
  
  CONCLUSIONS
  Parous women who develop IP have better functional outcome over time than nulliparous women who develop IP. The beneficial effect of parity diminishes with time.
authors.affiliation: Arthritis Research UK Epidemiology Unit, Manchester Academic Health Sciences Centre, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK.
authors.forename: E M
authors.initials: EM
authors.lastname: Camacho
authors.forename: M
authors.initials: M
authors.lastname: Harrison
authors.forename: T M
authors.initials: TM
authors.lastname: Farragher
authors.forename: M
authors.initials: M
authors.lastname: Lunt
authors.forename: D K
authors.initials: DK
authors.lastname: Bunn
authors.forename: S M M
authors.initials: SM
authors.lastname: Verstappen
authors.forename: D P M
authors.initials: DP
authors.lastname: Symmons
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000453:epidemiology / Q000503:physiopathology* / Q000534:rehabilitation; D004185:Disability Evaluation; D004739:England / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D011379:Prognosis; D017584:Reproductive History; D013997:Time Factors